Optical remote sensing of environment in Estonia and Baltic region
Abstract
Algorithms are derived to retrieve various state parameters of the
atmosphere, vegetation and ground surface by means of optical remotely
sensed data mainly using the inverse methods of the radiative transfer
theory. Different ground truth measurements are carried out to test the
respective algorithms. The continuos measurements of spectral atmospheric
transparency and of variable atmospheric constituents by means of a
sunphotometer are set up. Atmospheric ozon layer and aerosols and their
effect on the solar UV-radiation at the ground surface are studied. The
program packages of atmospheric correction of satellite images that rely
on the sunphotometer data are taken into a routine use. Methods to upscale
the sunphotometer data onto a larger area (whole satellite image) are
elaborated. Satellite images are transformed into the physical units of
reflectance factors and methods are elaborated to create the tractable
from the point-of-view of environmental changes time series in Estonia and
Baltic region. Fundamental radiative transfer characteristics are measured
in willow and alder plantations to be applied in the remote sensing and
productivity models of vegetation. The variability of time series of
Estonian climatic parameters and radiation climate in particular are
studied. The non-stationary time series of the global climate are
characterized from the point-of-view of their
persistence/anti-persistence. New field spectrometers are designed and
made to carry out ground-based remote sensing measurements.